Motor-control system



Patented Oct. 1929 UNIT-ED srATEs PATENT OFFICE- ROY J. WENSLE Y, OF PITTSBUItGH, fiENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA moron-cerium. SYSTEM Application filed March 1,

My invention relates to systems of control and it has particular relation to such systems as are employed in connection with elevators, hoists and similar machines.

The object of my invention is to provide dynamic braking means, for a motor, that is variable in accordance with certain positions of the elevator or machine.

Various systems have been employed for effecting variable dynamic braking, in order to more accurately control the stopping of a direct-current motor. In elevator systems it is of particular importance to so control the hoisting motor as to insure reasonably accurate stops under varying load conditions.

According to my system, a variable dynamic braking device is controlled by a cam mechanism connected to the hoisting machine, this mechanism being arranged to operate the dynamic braking device at any desired predetermined position of travel of the elevator car, after power is cut ofi by the car operator.

My invention will'be best understood by reference to the accompanying drawing, in which The single figure is a diagrammatic view of circuits and apparatus embodying my invention.

A hoisting motor 1, having an armature 2 and a field-magnet winding 3, is operatively connected through a reversing switch 4 and a line switch 5 to line conductors 6 and 7. Switch 5 is provided with dynamic braking contact members 8 for controlling a resistor 9, which may thereby be connected in circuit with armature 2. A starting resistor 11 and a controlling switch 12 therefor, may be employed in the customary manner. Any other suitable system of acceleration may be utilized. A hoisting drum 13 is driven by the armature 2 and is arranged in the usual man ner for controlling an elevator car 14 by means of one or more hoisting cables 15. An electromagnetic brake 16, of any well-known type, maintains the car 14 at any point of travel when the motor is inoperative.

A movable switch member 17 is pivotally mounted on a shaft 18 and one end of the switch member is arranged to successively en- 1923. Serial No. 622,183.

gage a plurality of stationary contact members 19, 20 and 21. A spring 22 is rovided for biasing switch member 17 towar the stationary contact members 19, 20 and 21, and an electromagnet having a coil 23 is arranged for opposing the operation of spring 22. The opposite end of switch 17 carries a roller 24. An adjustable cam device 25 is rotatably mounted upon a shaft 26 and mechanically connected, by means of a chain 27 or other suitable driving means, to drum 13. The cam device 25 is provided with a plurality of notches, each notch corresponding to a floor level or landing for the car 14, as indicated by the legends 1st, 2nd, etc. The device 25 is, of course, so geared to the drum 13 that the angular movement of said device corresponds to the vertical movement of the car 14. Between floor stops of the elevator, the roller 24 maintains switch 17 in its inoperative illustrated position. A switch 28 is mounted in the car 14 for controlling coil 23 to prevent cam device 25 from actuating switch 17 except as hereinafter described.

The operation of my invention may be set forth as follows:

Motor 1 is startedand controlled in the usual manner by means of reversing switch 4 and line switch 5, the latter being preferably controlled by means of car switch 28. Acceleration of the motor is accomplished in the usual manner by means of resistor 11 and accelerating switch 12. I

\Vhen the switch 5 occupies its upper or closed position, .resistor 9 is excluded from the motor circuit. Coil 23 is also energized upon the closure of. switch 28, so that dynamic braking switch member 17 is rendered ineffective during normal operation of the hoisting motor, irrespective of the position of cam device 25.

Vhen the car 14 approaches any desired landing, switch 28 is opened by the operator to release switch 5 and to de-energize coil 23. lVhen switch 5 assumes its illustratedposition, a dynamic braking circuit is established comprising the armature 2, dynamic braking contact members 8, resistor 9 and conductor 29. As the car 14 approaches the landing p ifiOIl, roller 24 gradually rolls into the notch, in the cam mechanism 25, corre-;: sponding to the particular landing. There-l fore, switch 17, which isbiased by means of I spring 22, successively engages stationary contact members, 19, 20 and 21 to gradually shunt portions of dynamic braking resistor 9 and accordingly increase the dynamic braking efi'ect upon the armature 2.' If the elevator is operating slowly, switch 17 is correspondingly operated and said portions of res1stor9 are, consequently, more gradually excluded." It is apparent that the dynamic I brakin control ed to a considerable degree in accord forms of dynamic braking effect on the motor 1 may thus be means for accomplishing variable or gradu-' atedfdynamic braking of a hoisting motor,

the raking becoming increasingly effective as the'car approaches any floor level. Other switch mecha- 'nism, as well as modifications of my cam i as I so

vpartingfrom t vention.

V mechanism, ma readily be made without de- Splnt and p of my f ing resistor disposed. to be connected across a I the motor terminals in response to the Oper- I claim as my invention:

- 11. The comblnation with a hoisting mech anism and 'a driving motorrtherefor, of a dynamic braking resistor, means for SIICCQS".

sively shunting portions of said resistor,

electro-rcsponsive means for rendering the shunting means inefiective,and a cam device controlled in accordancewith different positions of said hoisting mechanism for mechanically actuating said shunting means.'

2. The combination with an elevator mechanism and a driving motor therefor, of a dynamic braking resistor, means for successively shunting portions of said resistor,electro-responsive means for rendering the shunting means ineffective, and cam actuated means controlled in accordance-with the distance covered by the elevator'for actuating said shunting means.

3. The combination with anelevator meche anism and a driving motor therefor, ofa dynamic braking resistor, means for successively shunting portionsof said resistor, elec-' tro-responsive means for. rendering the shunting means inefiective, and a cam mechanism operated by the movement of the elevator for mechanically actuating said shunting means.

4. The combination with a hoisting mechanism and a driving motor therefor, of means for accelerating the motor, means for decelerating the motor comprising a resistor controlled by the hoisting mechanism for actuating said shunting means, a coil for rendermg said shunting means .inefiective and of said coil.

Y 5( In a-control system for hoisting meching the hoisting mechanism, a controller for controlling the energization of the motor, a dynamic braking resistor for the motor, a

anisms, in combination,a motor for operatspring-biased switch member for shunting the resistor to vary the braking force, a rotatably mounted cam for actuating the switch member, means for actuating the cam memher in accordance with the movements of the hoisting mechanism, said cam being pro vided with a plurality of cam faces one for each of a predetermined number of stopping positions, said faces being dis osed to control the movement of said switch member, I

whereby the resistance of the dynamic braking circuit is rendered dependent upon the position of the hoisting mechanism respect to a stopping position.

6. In a control system for hoisting -mech if anisms, in combination, a motor for operat;

ing the hoisting mechanism, a source of power for the motor, a switch for controlling the-operation of the motor, a dynamic brakation of said control switch, a movable switch cut sections of the resistor, and means acturated in accordance with the movement of the hoist for mechanically actuating the movable switch blade, said means being disposed to W vary the degree of brakingforce dependent upon the position of the hoisting mechanism when the control switch is o erated.

7 In a control system for oisting mechanis'ms, in combination, a motor for operating tions of the resistor, and means actuated in i accordance with the movement of the hoist for mechanically actuating the movable switch blade, said means being disposed to gradually effect a reduction in resistance of the dynamic braking circuit in response tothe opening of the control switch when the hoist is within a predetermined distance from the stopping position.

8. In a bination, a motor for actuating the hoist, a

control system for hoists, in comsource of power for the motor, a switch for controlling the operation of the motor, a dynamic braking resistor disposed to be con- 4 and means for successively shunting difien ent sections of'the resistor, a cam mechanism and a' cam member actuated in accordance with the movement of the hoist for actuating the contact arm, thereby to render the dynamic braking of the motor dependent upon the 5 position of the hoist. I

9. In a control system for hoisting mechanisms, in combination, a motor for operating the hoisting mechanism, a source of power for the motor, a dynamic braking resistor, a controller for governing the operation of the motor and establishing a dynamic braking circuit, said dynamic brakingcircuit havin a predetermined maximum resistance va no, and a mechanically actuated switch disposed to successively shunt sections of the resistor to reduce the resistance of the braking circuit, said switch having a rotatable cam shaped operating member driven in accordance with the movements of the hoisting 0 mechanism. Y

- 10. In a control system for hoisting mech anisms, in combination, a motor for operating the hoisting mechanism, a source of power for the motor, a dynamic braking resistor, a

controller for governing the operation of the motor and establishing a dynamic braking circuit, a pivotally mounted contact making arm for shunting sections of the resistor, the number of resistor sections shunted being dependent upon the position of the arm, a rotatable disc members driven in accordance with the movements of the hoisting mechanism for actuating the contact making arm,

- said disc member being provided with a plurality of cam faces disposed to engage said arm, whereby the resistanceiof the dynamic braking circuit may be varied in a predetermined manner at predetermined intervals in the travel of the hoisting mechanism.

11. In a control system for hoisting mechanisms, in combination, a motor for operating the hoisting mechanism, a source of power for the motor, a dynamic braking resistor, a controller for governingthe operation of the motor and establishing a dynamic braking circuit, a pivotally mounted switch member disposed to successively shunt difierent secfions of the resistor, said switch member be ing biased toward the shunting position, a

rotatably mounted cam for controlling the movement of the switch member, means for driving the cam in accordance with the movement of the hoisting mechanism, the face on the cam being adapted to effect the stopping of the hoist in different positions and means controlled by the motor controller for rendering the operation of switch member responsive to the movements of the cam to vary the resistance of the dynamic braking circuit 69 in accordance with the position of the hoist.

In testimony whereof, I have hereunto subscribed my name this 15th day of February BOY J. WENSLEY. 

